US4112389A - Diode laser with ring reflector - Google Patents

Diode laser with ring reflector Download PDF

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Publication number
US4112389A
US4112389A US05/761,110 US76111077A US4112389A US 4112389 A US4112389 A US 4112389A US 76111077 A US76111077 A US 76111077A US 4112389 A US4112389 A US 4112389A
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United States
Prior art keywords
ring
coupler
laser
light
section
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Expired - Lifetime
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US05/761,110
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English (en)
Inventor
William Streifer
Donald R. Scifres
Robert D. Burnham
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Xerox Corp
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Xerox Corp
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Priority to US05/761,110 priority Critical patent/US4112389A/en
Priority to CA294,814A priority patent/CA1091794A/en
Priority to JP232278A priority patent/JPS5392680A/ja
Priority to GB2211/78A priority patent/GB1556347A/en
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Publication of US4112389A publication Critical patent/US4112389A/en
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S5/00—Semiconductor lasers
    • H01S5/10—Construction or shape of the optical resonator, e.g. extended or external cavity, coupled cavities, bent-guide, varying width, thickness or composition of the active region
    • H01S5/1071—Ring-lasers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S5/00—Semiconductor lasers
    • H01S5/10—Construction or shape of the optical resonator, e.g. extended or external cavity, coupled cavities, bent-guide, varying width, thickness or composition of the active region

Definitions

  • the semiconductor diode laser in a p-n junction device which lases when a forward bias voltage of at least 1.5 volts is applied to the device.
  • the voltage drives either holes or electrons or both across the p-n junction and when the holes and electrons recombine they emit light.
  • the holes and electrons recombine they can be "stimulated" by light to emit more light coherently.
  • This stimulated emission phenomenon is equivalent to providing amplification and is related to the first of two requirements for laser oscillation. Specifically, a first requirement is that there be sufficient gain or amplification of the light within the laser to overcome all losses.
  • the second requirement for laser oscillation is an optical feedback mechanism.
  • Optical feedback is provided in conventional diode lasers by simply "cleaving" the faces of the semiconductor crystal. These cleaves form plane parallel mirror-like surfaces which reflect a portion of the light back into the region of the p-n junction. The reflected light is amplified and the energy density within the laser continues to build up to produce the very intense laser beam.
  • a diode laser which uses light wave interference to provide the optical feedback mechanism for the laser.
  • the pumped active region of the laser includes a section in the shape of a closed loop or ring which closes at a coupler section of the active region.
  • the path length of the closed loop or ring section is chosen so that a light wave beginning at the coupler section and traveling around the loop or ring section experiences a path length difference of ⁇ g /2 when it arrives back in the coupler section.
  • the two waves then interfer destructively and no power is transmitted into a waveguide connected to the coupler section. This means that the light wave that traversed the loop or ring section is reflected back into the loop or ring and thus optical feedback is provided without cleaved end faces or a distributed feedback structure.
  • a 3db coupler is preferred.
  • the loop or ring shaped section of the laser active region can have two couplers connected on opposite sides thereof. These couplers also reflect light at certain wavelengths due to interference phenomena, thus providing feedback. Depending on the symmetry of the couplers, the light output (or reflection) at the couplers can vary whereby light can be transmitted to a desired waveguide coupled to one of the couplers.
  • FIGS. 1, 1A and 1B show one form of semiconductor device in accordance with the invention.
  • FIG. 2 shows in cross-section another form of semiconductor device in accordance with the present invention.
  • FIGS. 3 and 3A show a semiconductor device in accordance with the invention with multiple waveguide connections.
  • FIGS. 1, 1A and 1B there is shown an embodiment of a semiconductor device 2 which utilizes destructive interference between light waves to provide an optical feedback mechanism.
  • Semiconductor device 2 includes substrate 4 and layers 5, 6, 8 and 10, and is divided into a ring laser portion 2a and a waveguide portion 2b.
  • Ring laser portion 2a includes a portion of substrate 4, a portion 5' of layer 5, a portion 6' of layer 6, and layers 8 and 10.
  • Portion 6' which constitutes the active region of the ring laser, includes a closed loop or ring-shaped section 6a which closes at a 3db coupler section 6b.
  • the 3db coupler section 6b connects the ring-shaped section 6a of the ring laser 2a to the waveguide section 6c of the waveguide portion 2b.
  • the layers 5', 8 and 10 have substantially the same shape as the portion 6' of the layer 6, that is, layers 5', 8 and 10 have the shape of a closed loop or ring.
  • the ring laser portion 2a is doped to provide a rectifying (p-n) junction at one surface of the active region portion 6'. With sufficient forward bias of the rectifying junction, carriers are driven across the rectifying junction where they combine with other carriers to emit light.
  • Layers 5 and 8 are of a material having a lower refractive index than the material of layer 6 to provide for light confinement.
  • the semiconductor device 2 can have, for example, the layer compositions and doping types shown in FIG. 1A. That double heterojunction structure provides a rectifying junction 12 between the portion 5' of layer 5 and the portion 6' of layer 6 and light emission when a sufficient forward bias is applied to rectifying junction 12 by electrodes 60 and 61. If the light generated in the portion 6' of layer 6 remains in the material from which it is generated, it would be absorbed within a short time.
  • the waveguide section 6c must have a different band gap than light generating and coupler sections 6a and 6b of layer 6. That difference in band gap can be achieved by having the section 6c doped oppositely to sections 6a and 6b, as shown in FIG. 1A.
  • light can be directed into a waveguide by butt-coupling between an active region of one conductivity type, and a waveguide region of the opposite conductivity type, as described in relation to FIG.
  • Optical feedback of the emitted light sufficient to provide lasing is provided by the ring-shaped section 6a and the 3db coupler section 6b of layer 6.
  • 3db coupler it is meant that the junction of the ring section 6a with the coupler section 6b is a symmetrical junction, that is, a light wave advancing toward the ring section from a point of the coupler section will be divided equally and send light waves of equal intensity around the loop in both directions.
  • Optical feedback sufficient to provide lasing is provided by interfering light waves in the 3db coupler section 6b.
  • a light wave (of wavelength ⁇ g), beginning at the 3db coupler section 6b and traveling in either direction around the ring-shaped section 6a, experiences a path length difference of ⁇ g/2 when it arrives back at its starting point in the 3db coupler section 6b, then the two waves, that is, the portion of the light wave that has traversed or circulated around the ring and the portion of the light wave which has not yet traversed or circulated around the ring, will destructively interfere and no power will be transmitted into the waveguide section 6c. In other words, if the returning light wave has a phase shift of 180° relative to its starting phase, the two waves are out of phase and destructively interfere.
  • the destructive interference causes the circulating light wave to be reflected back into the ring section 6a, thus providing optical feedback.
  • the ring laser 2a will oscillate at wavelengths corresponding to path lengths of p ⁇ + ⁇ /2 where p is an integer because these are the wavelengths at which the destruction (or reflection) is maximum and thus the wavelengths at which the laser threshold is lowest.
  • Output from the laser into the waveguide can be obtained by use of an assymetrical coupling section (not a 3db coupler). In this case one beam will be more intense than the one travelling in the opposite direction and thus partial reflection (and partial transmission) will be obtained.
  • an assymetrical coupling section not a 3db coupler
  • one beam will be more intense than the one travelling in the opposite direction and thus partial reflection (and partial transmission) will be obtained.
  • the coupler geometry the reflection and transmission properties can be optimized for the particular laser and waveguide use.
  • the semiconductor device of FIG. 1 can be made by conventional liquid phase epitaxy or molecular beam epitaxy growth techniques, and standard photolithographic masking and etching techniques.
  • the layers 5, 6, 8 and 10 can be grown on substrate 4 by conventional liquid phase epitaxial growth techniques, followed by the application of a resist mask, in the shape of a ring section and a straight coupler section, to the top surface of layer 10 and then the application of an acid etch to the top surface of layer 10.
  • the acid etch will remove those portions of the semiconductor material not protected by the resist mask.
  • the semiconductor device of FIG. 1 can be made by growing through a silicon nitride mask having the ring pattern. LPE growth occurs only through the opening in the nitride mask.
  • non-conducting regions are grown over the Si 3 N 4 portion while conducting regions are produced in the opening.
  • layers 5, 6, 8 and 10 may be grown with layer 6 being n-type.
  • a Si 3 N 4 ring shaped mask may be formed and Zn diffused to form p-type region 6'. This process produces both the coupler and ring geometry simultaneously.
  • the radius of the ring section 6a must be sufficiently large so that radiation losses around the ring are kept within limits that will provide light wave feedback of sufficient intensity to sustain lasing.
  • the radius of the ring section 6a should be greater than approximately 0.4 millimeters.
  • a smaller ring radius can be provided if the active region layer is sandwiched between layers having a substantially lower refractive index, as is true for a buried heterojunction device or etched mesa device 18 shown in cross section in FIG. 2.
  • Device 18 includes a substrate 20, a layer 21, an active region layer 22, light confining layers 24 and 26 bordering the layer 22, a contact facilitating layer 28 and electrodes 62 and 63.
  • the buried heterojunction or etched mesa device 18, which can be comprised of the materials and doping types shown in FIG. 2, operates on the same principles as the device of FIG. 1, but instead of butt-coupling utilizes a tapering 23 of the 3db coupling section of the active region layer 22 to direct light into a waveguide section provided by layer 24.
  • FIGS. 3 and 3A A diode laser capable of directing light waves into more than one waveguide is shown in FIGS. 3 and 3A.
  • the device of FIG. 3 includes a substrate 40, an active region layer 42, a light confining layer 44, a contact facilitating layer 46, and a rectifying junction 48 adjacent the active region layer.
  • the active region layer 42 includes a right waveguide and a left waveguide.
  • the principle of operation of the diode laser of FIG. 3 is identical to that described for the ring lasers of FIGS. 1 and 2 in that the couplers 49 and 50 reflect light at certain wavelengths due to destructive interference phenomena. Thus feedback is provided.
  • the light output (and reflection) can vary from one end to the other.
  • the ring diode laser of the invention can be either of the homojunction, single heterojunction or of the double heterojunction type.
  • other types of laser geometries can be used.
  • twin guide lasers having separate optical and carrier confinement, and buried heterostructure lasers can also be used.
  • distributed feedback and/or discrete reflectors can be used to replace one of the coupler sections of FIG. 3.

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  • Physics & Mathematics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • General Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Optics & Photonics (AREA)
  • Semiconductor Lasers (AREA)
  • Optical Integrated Circuits (AREA)
US05/761,110 1977-01-21 1977-01-21 Diode laser with ring reflector Expired - Lifetime US4112389A (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
US05/761,110 US4112389A (en) 1977-01-21 1977-01-21 Diode laser with ring reflector
CA294,814A CA1091794A (en) 1977-01-21 1978-01-12 Diode laser with ring reflector
JP232278A JPS5392680A (en) 1977-01-21 1978-01-12 Semiconductor laser
GB2211/78A GB1556347A (en) 1977-01-21 1978-01-19 Diode laser

Applications Claiming Priority (1)

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US05/761,110 US4112389A (en) 1977-01-21 1977-01-21 Diode laser with ring reflector

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US4112389A true US4112389A (en) 1978-09-05

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JP (1) JPS5392680A (ja)
CA (1) CA1091794A (ja)
GB (1) GB1556347A (ja)

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4297651A (en) * 1979-08-23 1981-10-27 Northern Telecom Limited Methods for simultaneous suppression of laser pulsations and continuous monitoring of output power
US4360921A (en) * 1980-09-17 1982-11-23 Xerox Corporation Monolithic laser scanning device
US4444459A (en) * 1981-06-29 1984-04-24 The Boeing Company Fiber optic slip ring
DE3632585A1 (de) * 1985-09-28 1987-04-02 Sharp Kk Halbleiterlaser
US4695121A (en) * 1985-01-28 1987-09-22 Polaroid Corporation Integrated optic resonant structres and fabrication method
US4851368A (en) * 1987-12-04 1989-07-25 Cornell Research Foundation, Inc. Method of making travelling wave semi-conductor laser
DE3802404A1 (de) * 1988-01-28 1989-08-03 Licentia Gmbh Halbleiterlaser
US5231642A (en) * 1992-05-08 1993-07-27 Spectra Diode Laboratories, Inc. Semiconductor ring and folded cavity lasers
US5398256A (en) * 1993-05-10 1995-03-14 The United States Of America As Represented By The United States Department Of Energy Interferometric ring lasers and optical devices
WO2013130065A1 (en) * 2012-02-29 2013-09-06 Hewlett-Packard Development Company, L.P. Unidirectional ring lasers

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3605037A (en) * 1969-05-02 1971-09-14 Bell Telephone Labor Inc Curved junction laser devices

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3605037A (en) * 1969-05-02 1971-09-14 Bell Telephone Labor Inc Curved junction laser devices

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
Elsa Garmire, "Moving Toward Integrated Optics", Laser Focus, Oct. 1975, pp. 55-59. *

Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4297651A (en) * 1979-08-23 1981-10-27 Northern Telecom Limited Methods for simultaneous suppression of laser pulsations and continuous monitoring of output power
US4360921A (en) * 1980-09-17 1982-11-23 Xerox Corporation Monolithic laser scanning device
US4444459A (en) * 1981-06-29 1984-04-24 The Boeing Company Fiber optic slip ring
US4695121A (en) * 1985-01-28 1987-09-22 Polaroid Corporation Integrated optic resonant structres and fabrication method
DE3632585A1 (de) * 1985-09-28 1987-04-02 Sharp Kk Halbleiterlaser
US4792962A (en) * 1985-09-28 1988-12-20 Sharp Kabushiki Kaisha A ring-shaped resonator type semiconductor laser device
US4851368A (en) * 1987-12-04 1989-07-25 Cornell Research Foundation, Inc. Method of making travelling wave semi-conductor laser
DE3802404A1 (de) * 1988-01-28 1989-08-03 Licentia Gmbh Halbleiterlaser
US5231642A (en) * 1992-05-08 1993-07-27 Spectra Diode Laboratories, Inc. Semiconductor ring and folded cavity lasers
US5398256A (en) * 1993-05-10 1995-03-14 The United States Of America As Represented By The United States Department Of Energy Interferometric ring lasers and optical devices
WO2013130065A1 (en) * 2012-02-29 2013-09-06 Hewlett-Packard Development Company, L.P. Unidirectional ring lasers
US9130342B2 (en) 2012-02-29 2015-09-08 Hewlett-Packard Development Company, L.P. Unidirectional ring lasers
EP2823539A4 (en) * 2012-02-29 2016-01-13 Hewlett Packard Development Co UNIDIRECTIONAL LASERS IN RING
US9419405B2 (en) 2012-02-29 2016-08-16 Hewlett Packard Enterprise Development Lp Unidirectional ring lasers

Also Published As

Publication number Publication date
JPS5392680A (en) 1978-08-14
CA1091794A (en) 1980-12-16
GB1556347A (en) 1979-11-21
JPS6140159B2 (ja) 1986-09-08

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